Thermal effect suppression of end-pumped rod-like Nd:YAG laser crystal utilizing the diamond cap strategy

In high-power laser systems, thermal lensing effects and thermal birefringence in laser gain media significantly impact beam quality and stability. This study simulates different end-capped structures of Nd:YAG gain media to assess their effect on thermal characteristics. Thermal lensing effects were evaluated through optical path differences and thermal focal lengths, while thermal birefringence effects were assessed using depolarization losses. Results show that diamond cap can reduce the peak temperature of the gain medium by 30.0 K. Optical path difference and thermal focal length changes confirm that diamond caps can minimize the thermal lensing effect. Moreover, the reduction of the depolarization loss suggests a reduction in the polarization state. Futhermore, this paper explores the optimization of diamond geometry to enhance laser system stability. Larger diamond radii and thicknesses prove more effective in diminishing optical path differences and depolarization loss, with changes in radius showing a significant impact on thermal performance. This research enhances laser stability and performance and lays a theoretical foundation for future laser thermal management strategies.